Fluid-pressure and analogous brake systems – Multiple systems
Reexamination Certificate
1999-06-07
2001-01-30
Butler, Douglas C. (Department: 3613)
Fluid-pressure and analogous brake systems
Multiple systems
C188S358000, C180S422000, C180S441000, C303S010000, C303S115400, C303S003000, C303S114100, C303S113400
Reexamination Certificate
active
06179389
ABSTRACT:
BACKGROUND OF THE INVENTION
This application claims the priority of 198 25 204.8-21, filed Jun. 5, 1998, the disclosure of which is expressly incorporated by reference herein.
The present invention relates to a system for generating a brake pressure with a pump which delivers a volume into the master brake cylinder chamber and builds up a pressure which is used by at least one additional assembly, particularly a power-assisted steering system, and having at least one distributing and throttling element for admitting a definable pressure to the master brake cylinder chamber and/or the additional assembly.
DE 196 40 456 A1 shows a system in which a plurality of distributing and throttling elements is used. Thereby, the pressure in the chamber of the master brake cylinder and/or of the additional assembly can be distributed and adjusted. The triggering of these distributing and throttling elements requires relatively high control expenditures and is also susceptible to disturbances.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an improved system for generating a brake pressure such that, while the control expenditures are minimal, an adjustment and a distribution of the brake pressure which is applied to the chamber of the master brake cylinder and to the additional assembly, can be implemented in a simple manner, which is not susceptible to disturbances and is adapted to the vehicle and the driving situation.
In a system for generating a brake pressure with a pump, this object has been achieved according to the present invention by providing that the at least one distributing and throttling element can be triggered as a function of the brake pedal position and/or of driving condition values and/or of operating values of the vehicle. Thus, the chamber and/or the additional assembly can be acted upon by an adjustable pressure which is pump generated.
The distributing and throttling element can be triggered as a function of the brake pedal position and/or of driving condition and/or operating values of the vehicle. Thereby, the chamber of the master brake cylinder and/or the additional assembly can be acted upon by an adjustable pressure generated by the pump, advantageously, as the result of supplying the brakes as well as the additional unit, for example, of a power-assisted steering system by the same pump. Not only the operational safety of the steering system and of the brake is increased but the pressures between the brake and the steering system can be distributed and adjusted such that driving-dynamic values can be influenced. Furthermore, the braking system and the steering system can be adapted in this manner to defined vehicle-specific or driver-specific configurations.
A particularly advantageous embodiment of the present invention provides that the distributing and throttling element comprises at least one controllable proportional valve through which the chamber and/or the additional assembly can be acted upon by an adjustable pressure.
In an advantageous embodiment, the distributing and throttling element is a 4/3-way proportional valve, in whose first switching position the additional assembly is connected unthrottled with the pump, and the chamber of the master brake cylinder is connected with a fluid storage tank; in whose second switching position, the chamber is connected with the pump in an unthrottled manner and the additional assembly is connected with the pump in a controllably throttled manner; and in whose third switching position, the additional assembly is connected with the pump in an unthrottled manner and the chamber of the master brake cylinder is connected with the fluid tank in a controllably throttled manner.
This controllably operable 4/3-way proportional valve makes possible virtually any pressure distribution between the vehicle brake and the additional assembly, for example, a power-assisted steering system.
In another advantageous embodiment, the distributing and throttling element comprises a 5/3-way valve, in whose first switching position, the chamber and the additional assembly can be acted upon by a pressure by way of a flow control valve in a throttled manner; in whose second switching position, only the additional assembly can be acted upon by pressure in an unthrottled manner; and in whose third switching position, the additional assembly and the chamber can be acted upon with pressure in an unthrottled manner; and in that, in the line leading to the chamber, a controllable 2/2-way flow control proportional valve is arranged whose outlet is connected with a fluid tank.
It is preferably provided that the delivery of the pump can be varied in a controlled manner as a function of the operating path of the master brake cylinder and/or of the extent of the operation of the additional assembly, preferably of the turning velocity of a steering wheel of the power-assisted steering system. As a result, a pressure increase or a pressure decrease can take place, if required, at the master brake cylinder and/or the additional assembly, i.e., the power-assisted steering system, without changing the switching position of the valves. The turning velocity or any other appropriate value can also be used to characterize the extent of the operation and thus the extent of the required pressure to be provided on the additional assembly, for example, the power-assisted steering system, in order to vary the delivery of the pump.
The other driving condition and/or operating values of the vehicle, as a function of which the controllably operable distributing and throttling element can be triggered, advantageously include the following values: Lateral wheel forces, normal wheel forces, the longitudinal or lateral inclination of the vehicle, the longitudinal or lateral acceleration of the vehicle, the aerodynamic drag, the lift forces and negative lifts of the vehicle, the load condition of the vehicle, and the driving forces at the driven wheels of the vehicle.
In order to achieve a variably adjustable intensification ratio between the pedal force or the pedal travel of the driver and the vehicle deceleration, another advantageous embodiment provides that, as the result of the controllably throttled introduction of volume delivered by the pump into the chamber of the master brake cylinder, the pedal force/travel deceleration characteristic of the vehicle is adjustable.
Still another advantageous embodiment provides that the brake force distribution can be adjusted as a function of a forward or reverse driving of the vehicle by way of throttled volume which can be controllably introduced into the chamber of the master brake cylinder. Also when the vehicle is reversing, a stable braking performance can be particularly advantageously ensured in this manner.
The triggering advantageously takes place by way of an electronic control unit so that the distributing and throttling element can be triggered as a function of the brake pedal position and of the additional operating values of the vehicle and of driving condition values.
It may advantageously be provided that the actual longitudinal vehicle deceleration can be supplied to the control unit and can be compared with other operating values of the vehicle and with driving condition values, particularly with the desired vehicle deceleration defined by the driver of the vehicle. In this manner, the braking performance of the vehicle can be made independent of disturbance variables, for example, of exterior forces acting upon the vehicle, such as the load condition, a trailer operation, a slope or gradient, headwind, and of interior forces, such as a coefficient of friction spreading of the brake linings or inaccuracies of the engine torque.
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patent: 2952281
Duvenbeck Michael
Freitag Rainer
M{umlaut over (u)}ller Armin
Ringer Franz
Troster Harry
Butler Douglas C.
Daimler-Chrysler AG
Evenson, McKeown, Edwards & Lenahan P.L.L.C.
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